The present invention relates generally to the field of telecommunications systems for the transmission of data, and, more specifically to those systems which assure privacy and integrity of communications by providing for verification of the identity of the sender and/or the receiver, authentication of the message and encrypting/decrypting of the message content.
The use of computers and telecommunications networks to deliver messages containing critical data and value-related transfers is restrained by uncertainty of the identity of the party at the other end of the connection and by uncertainty of the integrity of the message content.
A limited degree of certainty and integrity is attained by controlling the physical attributes of the network and the handling of the message; by restricting the number of participants in a network, by limiting the devices and communication lines that can be used, by requiring special access features such as plastic cards and by prescribing the message format to be employed.
Another alternative is to control the message itself; to transform the message so that it is intelligible only to the intended party or to express it in a private language.
Both solutions depend on isolating each network from all others. Many networks have been established using one or both of these solutions. They are successful in serving specific groups of users for particular purposes. They are not suitable as a foundation for universal electronic transaction services. Further, since proprietary systems and encrypted messages forego economies of scale to attain the isolation that permits control they are too expensive to serve the great number of critical-data and value-related messages now processed through paper-based systems. The most important example is found in banking where 40 billion paper checks are processed each year.